Implement web API synchrony
o A locking/blocking setattr/getattr version of cpppo.dotdict was
  implemented called apidict.  Setting/getting values by index
  locks but doesn't block, while setting attributes blocks 'til
  a getattr is executed (in another thread).
o The cpppo.network.server_main and server_thread now respond to
  a package of server.control... parameters.
o cpppo.network.server_main was modified to allow provision of
  a different server_thread class, if desired.